A novel cochaperonin that modulates the ATPase activity of cytoplasmic chaperonin.

Gao, Yuanfeng; Melki, Ronald; Walden, Paul D.; Lewis, Sally A.; Ampè, Christophe; Rommelaere, Heidi; Vandekerckhove, Joël; Cowan, Nicholas J.

doi:10.1083/jcb.125.5.989

Cited by 80 publications

(73 citation statements)

References 43 publications

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“…Although averaged images of the particle with and without bound substrate have been presented (Marco et al, 1994), detailed information about the structural and biochemical properties of the eukaryotic chaperonin particle is still sparse. This may be due in part to the limitations of isolation procedures that rely on size fractionation, limited capacity affinity supports, and laborious folding assays (Frydman et al, 1992;Gao et al, 1992;Lewis et al, 1992).…”

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confidence: 99%

Novel isolation method and structural stability of a eukaryotic chaperonin: The TCP‐1 ring complex from rabbit reticulocytes

Norcum

1996

Protein Science

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In the course of removing a contaminant from preparations of aminoacyl-tRNA synthetase complexes, a novel purification method has been developed for the eukaryotic cytoplasmic chaperonin known as TRiC or CCT. This method uses only three steps: ammonium sulfate precipitation, pelleting into a sucrose cushion, and heparin-agarose chromatography. As judged by electrophoresis, sedimentation, and electron microscopy, the preparations are homogeneous. The particle is identified as a chaperonin from electrophoretic polypeptide pattern, electron microscopic images, direct mass measurement by sedimentation velocity analysis, amino-terminal sequencing, and ATP-dependent refolding of rhodanese and actin.Further investigation of the biochemical and physical properties of the particle demonstrates that its constituent polypeptides are not glycosylated. The particle as a whole binds strongly to polyanionic matrices. Of particular note is that negatively stained images of chaperonin adsorbed to a single carbon layer are distinctly different from those where it is sandwiched between two layers. In the former, the "characteristic" ring and four-stripe barrel predominate. In the latter, most images are round with a highly reticulated surface, the average particle diameter increases from 15 to 18 nm, and additional side, end, and substrate-containing views are observed. The particle structure is strikingly resistant to physical forces (long-term storage, repeated cycles of freezing and thawing, sedimentation), detergents (Triton, deoxycholate), salts (molar levels of KC1 or LiCl), and pH changes (9-6). Only a strongly chaotropic salt (NaSCN) and extremely acidic conditions (pH 4.5) cause aggregation and dissociation of TRiC, respectively. However, treatment with KC1 or deoxycholate reduces TRiC folding activity.

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confidence: 99%

Novel isolation method and structural stability of a eukaryotic chaperonin: The TCP‐1 ring complex from rabbit reticulocytes

Norcum

1996

Protein Science

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“…Gao et al (1994) cloned the mouse p14 cDNA and found no significant homologies to other known genes. These authors have suggested that p14 is the CCT cochaperThe basic microtubule units are tubulin dimers which are formed from c1-and B-tubulin monomers.…”

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confidence: 99%

The β‐tubulin monomer release factor (p14) has homology with a region of the DnaJ protein

et al. 1996

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p14 is a molecular chaperone involved in btubulin folding which catalyzes the release of ~tubulin monomers from intermediate complexes. Here we demostrate that active p14 protein which we have purified from an overproducing Escherichiu co/i strain can also release ~tubulin monomers from tubulin dimers in the presence of an additional cofactor (Z). Analysis of p14 secondary structure suggests that this protein may belong to a family of conserved proteins which share structural similarities with the Jdomain of DnaJ. We have constructed deletions and site-directed mutations in the ~14 gene. A single D to E mutation in the region shown in DnaJ to be an essential loop for its function affected the monomer-release activity of ~14. These results support the hypothesis that this p14 loop interacts with P_ tubulin in a similar fashion as DnaJ interacts with DnaK and suggest a possible role of p14 in the folding process.

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“…Whereas fully functional actin and ␥-tubulin polypeptides are released from the cytosolic chaperonin complex, ␣-tubulin and ␤-tubulin polypeptides are further processed by tubulin-folding cofactors (TFCs; for review, see Lewis et al 1997;Nogales 2000). TFCs were originally identified by their tubulin-folding activity in extracts from mammalian cells (Gao et al 1994;Llosa et al 1996;Melki et al 1996; Tian et al Cold Spring Harbor Laboratory Press on May 9, 2018 -Published by genesdev.cshlp.org Downloaded from …”

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The Arabidopsis PILZ group genes encode tubulin-folding cofactor orthologs required for cell division but not cell growth

Steinborn¹,

Maulbetsch²,

Priester³

et al. 2002

Genes Dev.

162

130

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Plant microtubules are organized into specific cell cycle-dependent arrays that have been implicated in diverse cellular processes, including cell division and organized cell expansion. Mutations in four Arabidopsis genes collectively called the PILZ group result in lethal embryos that consist of one or a few grossly enlarged cells. The mutant embryos lack microtubules but not actin filaments. Whereas the cytokinesis-specific syntaxin KNOLLE is not localized properly, trafficking of the putative auxin efflux carrier PIN1 to the plasma membrane is normal. The four PILZ group genes were isolated by map-based cloning and are shown to encode orthologs of mammalian tubulin-folding cofactors (TFCs) C, D, and E, and associated small G-protein Arl2 that mediate the formation of ␣/␤-tubulin heterodimers in vitro. The TFC C ortholog, PORCINO, was detected in cytosolic protein complexes and did not colocalize with microtubules. Another gene with a related, although weaker, embryo-lethal phenotype, KIESEL, was shown to encode a TFC A ortholog. Our genetic ablation of microtubules shows their requirement in cell division and vesicle trafficking during cytokinesis, whereas cell growth is mediated by microtubule-independent vesicle trafficking to the plasma membrane during interphase. The microtubule cytoskeleton plays important roles in both nondividing and dividing cells of eukaryotes, assisting in vesicle trafficking and mediating proper segregation of daughter chromosomes to opposite poles during mitosis (for review, see Cole and Lippincott-Schwartz 1995;Straight and Field 2000). In fission yeast, microtubules have also been implicated in maintaining cell shape and polarity (Sawin and Nurse 1998). Higher-plant cells form their own specific microtubule arrays, such as cortical hoops of interphase microtubules that organize cell elongation (Whittington et al. 2001), and two arrays related to the plant-specific mode of cell division (for review, see Lloyd and Hussey 2001). The preprophase band forms transiently at the onset of mitosis and marks the cortical division site (for review, see Smith 2001). The phragmoplast forms at the center of the division plane in late anaphase and guides the delivery of Golgiderived vesicles. Their fusion results in the formation and lateral expansion of the cell plate that matures into a cell wall and flanking plasma membranes (for review, see Staehelin and Hepler 1996). Both preprophase band and phragmoplast also contain actin filaments; however, their specific role in plant cell division is not understood at present (Smith 2001).Microtubules are polymerized from ␣/␤-tubulin heterodimers (for review, see Nogales 2000). Newly synthesized ␣-and ␤-tubulin polypeptides undergo a sequence of folding steps catalyzed by chaperones. Initially, the tubulins are associated with the hexameric prefoldin complex that passes them on to the cytosolic chaperonin complex (Geissler et al. 1998;Vainberg et al. 1998;Hansen et al. 1999; for review, see Leroux and Hartl 2000;Llorca et al. 2000). Whereas fully func...

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A novel cochaperonin that modulates the ATPase activity of cytoplasmic chaperonin.

Cited by 80 publications

References 43 publications

Novel isolation method and structural stability of a eukaryotic chaperonin: The TCP‐1 ring complex from rabbit reticulocytes

Novel isolation method and structural stability of a eukaryotic chaperonin: The TCP‐1 ring complex from rabbit reticulocytes

The β‐tubulin monomer release factor (p14) has homology with a region of the DnaJ protein

The Arabidopsis PILZ group genes encode tubulin-folding cofactor orthologs required for cell division but not cell growth

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